Function SignatureHash

test/functional/test_framework/script.py:860–908

Consensus-correct SignatureHash Returns (hash, err) to precisely match the consensus-critical behavior of the SIGHASH_SINGLE bug. (inIdx is *not* checked for validity)

(script, txTo, inIdx, hashtype)

def SignatureHash(script, txTo, inIdx, hashtype):
    """Consensus-correct SignatureHash

    Returns (hash, err) to precisely match the consensus-critical behavior of
    the SIGHASH_SINGLE bug. (inIdx is *not* checked for validity)
    """
    HASH_ONE = b'\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

    if inIdx >= len(txTo.vin):
        return (HASH_ONE, "inIdx %d out of range (%d)" % (inIdx, len(txTo.vin)))
    txtmp = CTransaction(txTo)

    for txin in txtmp.vin:
        txin.scriptSig = b''
    txtmp.vin[inIdx].scriptSig = FindAndDelete(script, CScript([OP_CODESEPARATOR]))

    if (hashtype & 0x1f) == SIGHASH_NONE:
        txtmp.vout = []

        for i in range(len(txtmp.vin)):
            if i != inIdx:
                txtmp.vin[i].nSequence = 0

    elif (hashtype & 0x1f) == SIGHASH_SINGLE:
        outIdx = inIdx
        if outIdx >= len(txtmp.vout):
            return (HASH_ONE, "outIdx %d out of range (%d)" % (outIdx, len(txtmp.vout)))

        tmp = txtmp.vout[outIdx]
        txtmp.vout = []
        for i in range(outIdx):
            txtmp.vout.append(CTxOut(-1))
        txtmp.vout.append(tmp)

        for i in range(len(txtmp.vin)):
            if i != inIdx:
                txtmp.vin[i].nSequence = 0

    if hashtype & SIGHASH_ANYONECANPAY:
        tmp = txtmp.vin[inIdx]
        txtmp.vin = []
        txtmp.vin.append(tmp)

    s = txtmp.serialize()
    s += struct.pack(b"<I", hashtype)

    hash = hash256(s)

    return (hash, None)

# TODO: Allow cached hashPrevouts/hashSequence/hashOutputs to be provided.
# Performance optimization probably not necessary for python tests, however.